DESCRIPTION OF THE PRIOR ART
A pre-Ex search of the art was made since double diaphragm pumps are well known. The use of diaphragms to pump fluids, particularly chemicals, is also well known. Slide valve control of the pump actuation is also known as evidenced by U.S. Pat. No. 3,838,946 to Schall as issued on Oct. 1, 1974. Also to be noted in particular in U.S. Pat. No. 3,860,034 to Rupp as issued Jan. 14, 1975.
In the present apparatus is provided a double diaphragm pump in which the diaphragms are actuated by a single shaft or rod. A slide valve is actuated by pressurized fluid which includes gas, air, oil or water and as air is one of the least expensive of these "air" is used to define any and all. This slide valve is moved to selectively admit pressurized air to a valve which passes the pressurized air to one side of the diaphragm to provide one-half the stroke. The shaft also moves the other diaphragm and disks attached to the shaft. This movement of the attached disks controls the effective pump stroke in each diaphragm chamber.
Slide valve control of double diaphragm pumps and single shafts that connect the two diaphragms are shown in prior art patents. The present invention provides a simple dual diaphragm pump with a pilot valve actuated by and with the movement of the shaft and disks carried thereon. These disks can and may be adjusted to vary the pumping action from the chambers. Pressurized air is contemplated for actuating the pump. The adjusting of the stroke actuation so that one chamber may pump one volume of fluid and the other diaphragm chamber pump another volume is provided by the present apparatus.